Photosynthesis
Photosynthesis is how plants use light, water, and air to make their own food and grow.
A leaf works like a kitchen mixing bowl that runs on sunlight. Water soaks up from the roots into the bowl. Air flows in and adds carbon dioxide. Sunlight hits the bowl and fuses the water and air into sugar, which the plant eats as food.
Explaining photosynthesis by grade level
Plants need light to make their food. That is why a plant near a fish tank can grow so well. The fish breathe out a gas that helps the plant. The plant takes in that gas, plus light and water, to feed itself.
Projects that explore photosynthesis
Chlorophyll — the green pigment that powers photosynthesis — does more than make food for a plant. It also masks other colors hiding in the leaf all summer long. When chlorophyll breaks down in fall, those hidden pigments finally show through. This project uses chromatography to separate them: tear leaves into small pieces, soak them in rubbing alcohol, then dip a coffee filter strip into the liquid. As the alcohol travels up the paper, each pigment moves a different distance, revealing bands of green, yellow, and sometimes orange or red.
Plants need carbon dioxide from the air to carry out photosynthesis and make food. Goldfish in an aquarium produce carbon dioxide and waste that nearby Elodea plants can absorb. When more fish share a tank, more of that key ingredient becomes available. This experiment tests whether that matters: four identical tanks hold three Elodea plants each, with zero, one, five, or ten goldfish. After seven days under the same light and filtration, you measure each plant and calculate average growth to see whether more fish leads to taller plants.